Fumigation of containerized cargo

ABSTRACT

An apparatus and method for tarpless fumigation of containerized cargo within a shipping container is disclosed. A portable fumigation containment door is installed in covering relation with main rear opening of a standard cargo container. Pneumatic cylinders are actuated to secure the door in place, and an inflatable gasket extending around the perimeter of the containment door and is inflated to create an airtight seal between the cargo container and the containment door. The door is provided with a series of connection ports for receiving fumigant injection and sampling lines necessary for performing the fumigation process.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/429,287, filed on Apr. 24, 2009, which claims the benefit ofprovisional U.S. Patent Application Ser. No. 61/049,154, filed on Apr.30, 2008.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT N/ACOPYRIGHT NOTICE

A portion of the disclosure of this patent document contains materialthat is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor patent disclosure as it appears in the Patent and Trademark Officepatent file or records, but otherwise reserves all copyrights rightswhatsoever.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a system and method forfumigating containerized cargo without the use of tarpaulin, and moreparticularly to such a system and method that utilizes a speciallyadapted portable containment door that creates a seal around the mainopening of the shipping container and provides the necessary connectioninlets and outlets for fumigant injection and sampling lines.

2. Description of Related Art

Containerization of cargo has revolutionized the shipping industry byincreasing efficiency through the creation of standardized shippingcontainers that are designed for movement through all major modes oftransportation, including cargo ships, trucks, and railroad cars. Due tosuch increases in efficiency, and improvement in refrigerated shippingcontainer designs, a wide variety of products, are now shippedthroughout the world. With an increase in the availability of a widerange of products, including perishable items, the risk of transportingharmful pests from one country to another along with the shipped goodsalso is enhanced. Foreign pests often have the potential of endangeringindigenous agriculture and wildlife, thereby causing widespread problemswithin existing agriculture systems. As a result, a large number oftransported cargo, particularly produce, must be fumigated upon arrivalin certain destinations.

The standards of the method for fumigating cargo containers areestablished by the Plant Protection and Quarantine (PPQ) branch of theUnited States Department of Agriculture (USDA) and are detailedextensively. According to the current conventional method for thefumigation of containerized cargo, a tarpaulin is placed over the singlecontainer unit or multiple container units that are being fumigated. Thecargo is arranged within the container in a manner such that the gasfumigant effectively circulates and penetrates the stored substances. Aseries of fans are introduced inside of the container, in order tocreate a flow of the fumigant. After the fans are placed, gasintroduction lines are positioned behind the fans through the main reardoors of the container. At least three gas sampling tubes are placed inspecific locations within the bulk containerized cargo and are used toactively monitor the concentration of the fumigant within the cargoduring the fumigation process. The containers are typically largeshipping containers, however, the tarpaulin method can be used withsmaller containers.

Once the fans, sampling tubes, and introduction lines are positioned,one or more tarpaulins are simply draped over the cargo containers andsealed along the ground through either loose or wet sand, sand snakes,water snakes, weights, adhesives, or any other suitable sealing means.After the tarpaulin is sealed, the amount (typically by weight) offumigant required is calculated based on the contained volume. Once theamount is determined, a gaseous fumigant, such as methyl bromide, iscaused to flow through at least one introduction line into the containedvolume and hence through the open doors of the tarpaulin coveredshipping containers. The fumigant is allowed to flow into the tarpaulinconfined space until calculated amount has been introduced. The fumigantconcentration level is subsequently sampled, typically using threesampling tubes, to determine whether a predetermined concentration levelhas been achieved throughout the contained volume. If the concentrationlevel is too low, then additional fumigant may be introduced.Conversely, if the concentration level is too high, then the fumigationtime may be reduced. Upon completion of the fumigation phase, the volumeis aerated through a method that is in accordance with treatmentguidelines and/or the Fumigator's PPQ compliance requirements. Themethod of aeration typically involves placing fans and exhaust ductsunderneath the tarpaulin so that the fumigant is evacuated into theatmosphere in a controlled manner. Once the container is sufficientlyaerated, typically to less than 5.0 parts-per-million (5.0 ppm) formethyl bromide, the tarpaulin is removed, and the cargo is subsequentlyreleased.

There are many problems associated with using the tarpaulin method forfumigation containerized cargo. First, if performed outside of anenclosed environment, the tarpaulin method of fumigation can only beperformed in certain weather conditions, specifically low windsituations. Also, the tarpaulin method is time consuming requiring theplacement of a large tarpaulin. Furthermore, during placement andstorage the tarpaulin can be damaged by the corners of the containers orother sharp objects, thereby leading to leaks. Finally, many problemshave arisen related to the toxicity and ozone depletion characteristicsof many used fumigants, especially methyl bromide. Tarpaulins areextremely difficult to completely seal off, leading to the inevitablerelease of fumigants during the fumigation process. Also the tarpaulinencases a much larger volume than just the container compartment,requiring the use of excess fumigant to adequately fumigate the contentsof the cargo container. In turn this excess fumigant is still ventedinto the atmosphere during the aeration process, leading to greaterenvironmental damage.

As a result of the numerous disadvantages present with the conventionaltarpaulin fumigation method, the background art reveals at least oneattempt directed to fumigation of containerized cargo without the use oftarpaulin. U.S. Pat. No. 6,403,027, issued to Napoles et al on Jun. 11,2002 describes such a method for fumigating cargo containers without theuse of a tarpaulin. That method, commonly generally described as a“tarpless fumigation method,” eliminates the need for a tarpaulin byusing the cargo container as an enclosure for containing the fumigantduring the fumigation process. The method includes placing fans and gassampling tubes within the cargo container, and threading the electricallines of the fans and the lines of the gas sampling tube out through apreexisting drain hole in the bottom of the cargo container. The gasintroduction line is placed through another preexisting drain hole. Theused drain holes are then sealed using a commercially available sealant,while the unused drain holes are plugged using any suitable means.Finally, after the main rear cargo doors are closed, the fumigant isflowed into the cargo container, and the contents of the cargo containerare subsequently fumigated. While the method disclosed by Napolesreduces the amount of space that must be filled with fumigant, it isstill prone to leaks. Specifically, it has been found that the main reardoors on a large number of shipping containers, particularly oldercontainers, are damaged, not airtight, or otherwise incapable ofmaintaining an adequate seal thereby leading to the fumigant leakagefrom the container directly into the surrounding atmosphere.

There therefore exists a need for an apparatus and method for fumigatingcontainerized cargo that does not utilize a tarpaulin and is bothinstallable and operated in a quick and easy manner. Furthermore, thissystem must minimize the amount of fumigant that is used and limit theamount of fumigant that leaks out during the fumigation process.

BRIEF SUMMARY OF THE INVENTION

The present invention overcomes the limitations and disadvantages in theart by providing a portable fumigation containment door apparatus forremovable temporary installation in covering relation with main rearopening of a standard cargo container. A series of pneumatic cylindersare used to lock the portable containment door in place on the cargocontainer by extending cylindrical bolts into engagement with thecontainer. An inflatable gasket extends around the perimeter of thecontainment door and is selectively inflated in order to create a sealbetween the cargo container and the containment door. The outer surfaceof the containment door has a series of connection ports for receivingthe lines that are necessary for performing the fumigation process. Someof those ports are in fluid communication with corresponding connectorson the inner surface of the containment door. Such connecting apparatusinclude pneumatic connectors, gas line connectors, and an electricalline connector. The pneumatic connector is provided to couple apressurized air source to the apparatus to allow for inflation of theperipheral sealing gasket. The gas line connectors are used to couple agas introduction line for flowing fumigant into the storage container,and multiple reading lines for flowing sampled fumigant out of thecontainer during the fumigation process. The inner surface of the deviceincludes a gas flow line connector that is used to connect the mainintroduction line through which the gas is flowed into the chamber at aspecific position. A series of other flow line connectors serve toconnect the gas sampling lines that provided the outflow of sampled gasfrom within the container. Finally, the inner surface of the devicecontains an electrical connector that serves as a means of providingpower to the fans inside of the storage container as are required by PPQstandards for the creation of a flow of fumigant within the containedvolume. A sealable hatch on the containment door allows the user tocouple the lines to the connectors on the inner surface once the door ispositioned around the rear opening of the cargo container.

The method of fumigation of the present invention includes: (a) fullyopening and securing the shipping container doors; (b) placing at leastone circulation fan, a tubular fumigant introduction line, and threetubular gas monitoring lines in specific positions within the cargocontainer; (c) installing corner block seals, and placing thecontainment door apparatus in inserted covering relation with the cargocontainer rear opening; (d) securing the containment door by actuationof pneumatic cylinders to extend bolts into engagement with the shippingcontainer; (e) inflating the peripheral gasket to create a seal betweenthe containment door and the shipping container; (f) opening the accesshatch and connecting the various sampling and fan power lines using theinner surface connectors provided on the inside surface of thecontainment door; (g) sealing openings and outside air intakes on theshipping container using any suitable means; and (h) injecting asuitable vaporized fumigant into the container via the fumigant shootingline; and (i) monitoring fumigant concentration.

Accordingly, it is an object of the present invention to provide asystem and method for fumigating containerized cargo without the use ofa tarpaulin (e.g. a “tarpless” method).

It is another object of the present invention to provide a tarplesssystem and method for fumigating containerized cargo that minimizes theamount of fumigant required to perform the fumigation.

It is yet another object of the present invention to provide a tarplesssystem and method for fumigating containerized cargo that minimizes theamount of fumigant that is required to perform the fumigation byintroducing the fumigant into a volume defined by the container that isused to hold the cargo.

It is still another object of the present invention to provide atarpless system and method for fumigating containerized cargo thatminimizes the amount of fumigant required to perform the fumigation bylimiting the amount of fumigant that is leaked during the fumigationprocess.

It is furthermore another object of the present invention to provide atarpless system and method for fumigating containerized cargo thatminimizes the amount of fumigant required to perform the fumigation bylimiting the amount of fumigant that is leaked during the fumigationprocess by using a portable containment door to cover and seal the mainrear opening of a cargo container.

It is still yet another object of the present invention to provide atarpless method and system for fumigation containerized cargo that isquickly and easily operated and performed.

In accordance with these and other objects, which will become apparenthereinafter, the instant invention will now be described with particularreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 depicts a trailer mounted shipping cargo container covered bytarpaulin for fumigation in accordance with the accepted prior artmethod;

FIG. 2 is a top outer side perspective view of a fumigation containmentdoor apparatus in accordance with the present invention;

FIG. 3 is a top perspective view showing the fumigation containment doorin relation to the open end of a shipping container;

FIGS. 4 and 5 illustrate the use of pneumatic cylinders to engage theshipping container for securing the fumigation containment doorapparatus;

FIG. 6 is a front (outer side) view of a fumigation containment door inaccordance with the present invention;

FIG. 7 is a side view thereof;

FIG. 8 is a rear (inner side) view thereof;

FIGS. 9-11 are partial sectional views showing the peripheral sealinggasket in detail;

FIG. 12 is a top view of the fumigation containment door;

FIG. 13 is a partial detail view showing the connection ports and accessdoor portion of the fumigation containment door; and

FIG. 14 is a schematic diagram of the fumigation system.

DETAILED DESCRIPTION OF THE INVENTION

With reference now to the drawings, FIG. 1 illustrates a cargo containercovered by tarpaulin in accordance with accepted prior art fumigationmethods, and FIGS. 2-14 depict and illustrate fumigation ofcontainerized cargo in accordance with the present invention. As bestseen in FIGS. 2 and 3, a portable fumigation containment door 10 isprovided. Fumigation containment door 10 is sized to fit within the rearopening of a cargo container. In accordance with a preferred embodiment,door 10 is generally square or rectangular in shape and designed to fitwithin the standard 7′ 8¼″ width and 7′ 5¾″ height of the main rearaperture opening of cargo containers with the standard lengths of 20′,40′, 45′, 48′, or 53′. As should be apparent, the overall dimensions maybe altered to fit any size or shape opening. Door 10 may be fabricatedfrom metal, such as steel or aluminum, composite material, such asfiberglass or carbon composite, or any other suitable material. In apreferred embodiment, door 10 is fabricated primarily from aluminum.

Door 10 includes a main body 11 having channel members 12 affixedthereto. Each channel member 12 extends from the outer surface of mainbody 11 and functions as a lifting lug by receiving the prongs of aforklift (not shown). The forklift is preferably adapted by attachmentof vertical members, sized for insertion into channel members 12,attached to the ends of the lifting forks. By operatively engaging theforklift, a quick and effective means is provided for lifting andpositioning the containment door 10 into and out of the main rearopening of the cargo container. While the present invention disclosesthe channel member and to forklift combination to lift and place door10, the present invention contemplates any suitable alternate structureto maneuver the door. Fumigation containment door 10 further includes asealable hatch 14 provides access to the inner chamber of the cargocontainer through the portable containment door 10 when it is positionedto cover the rear opening of the cargo container. Hatch 14 is connectedto door 10 by hinge and latch structures and configurable between openand closed positions. The latching mechanism is used to securely closethe hatch 14 and ensure that a seal is formed around the hatch 14.

As best seen in FIGS. 2 and 3, a plurality of pneumatic cylinders 16 arepositioned in proximity to the outer edges of the containment door 10,with each cylinder 16 oriented in a laterally outward direction relativeto containment door 10. Each pneumatic cylinder 16 is connected to twoair flow lines that are shielded by a spline 18. Each air flow line isadapted for selective fluid communication with a pressurized gas source,such as compressed air. A first air flow line is used to provide thecompressed air to a first cylinder inlet causing the outstroke actuationof the piston member of each pneumatic cylinder 16, and a second airflow line is used to provide compressed air to a second cylinder inletcausing the instroke actuation of the piston member. Spline 18 shieldsthe air flow lines thereby protecting against damage. Pneumaticcylinders 16 function to secure door 10 in the rear opening of a cargocontainer. As best seen in FIGS. 4 and 5, each pneumatic cylinderincludes a piston 16 a that fits into grooved flanges 20 that extendfrom the back of the cargo container. Container flanges 20 supporthinges 22 that allow for movement of the doors 24 of the rear cargobetween an opened and closed position. By fitting into the groovedflange, pistons 16 a of the pneumatic cylinders 16 remain in contactwith the grooved flanges, thereby limiting the movement of the portablecontainment door 10 and locking it into a desired position.

Fumigation containment door 10 further includes an inflatable sealinggasket 26 extending completely around the peripheral edge. Gasket 26comprises an inflatable gasket and is preferably fabricated fromflexible material that is characterized as being resistant to chemicalcorrosion due to its repeated exposure to concentrations of methylbromide. In a preferred embodiment, the material identified as Nitrilehas been found to provide a suitable gasket forming material. As bestillustrated in FIGS. 9-11, gasket 26 defines a generally T-shapedsemi-rigid portion, referenced as 26 a that extends transversally acrossthe side edge of door 10. Gasket 26 is removably connected to door 10 byfirst and second angle brackets 24 and 25. In a preferred embodimentfirst angle bracket 24 is permanently affixed to the outer side of door10, and second angle bracket 25 is removably attached thereto bythreaded fasteners 27. The T-shaped portion 26 a of gasket 26 issandwiched between the door edge and brackets 24 and 25 as seen in FIG.9. While the bracket configuration is disclosed in connection with thispreferred embodiment, any suitable gasket retaining means is consideredwithin the scope of the present invention.

In the preferred embodiment inflatable gasket 26 extends completelyaround the periphery of door 10 to provide a complete peripheral seal.Gasket 26 is selectively configurable between a non-inflatedconfiguration as seen in FIG. 9 and an inflated configuration as seen inFIG. 10, by an inflation valve. More particularly, gasket 26 includes aflexible bubble shaped region 26 b that extends from the T-shaped base26 a. Bubble shaped region 26 b is flexible thereby allowing it toexpand and contract with the inflating and deflating of the gasket 26.As the flexible bubble shaped gasket region 26 b expands as a result ofinflation, the outside of the bubble shaped gasket region 26 b makecontact with and subsequently exerts an outward force against the wallsof the rear opening of the cargo container. Through this outwardlyexerted force, a seal is created between the portable containment door10 and the cargo container. This seal minimizes the amount of fumigantthat escapes from the cargo container during the fumigant process,thereby lowering the overall amount of fumigant that is used during thefumigation process. As best seen in FIG. 2, door 10 has generallyrounded or radiussed corners. Accordingly, the present invention furtherprovides corner seals 19. Each corner seal 19 preferably comprises agenerally triangular sealing structure having straight legs disposed at90 degrees and a concavely radiussed hypotenuse. Corner seals 19 arepreferably positioned so as to engage the corners of the cargo containerwith the radiussed hypotenuse engaging one of the convex corners of door10. Corner seals 19 may be adhesively secured to the corners of door 10.

A line connection housing 30 is disposed on door 10 adjacent to thehatch 14 on the outer surface of the portable containment door. The lineconnection housing 30 is preferably a separated region on the outersurface of the door that contains all of the connection ports necessaryfor performing the fumigation. The line connection housing 30 can beplaced anywhere on the outer surface of the potable containment door 10as is convenient for the performing of the fumigation. As best seen inFIG. 13, line connection housing 30 includes a plurality of connectionports. The connection ports include first and second pneumaticconnection ports, referenced as 32 a and 32 b, each of which is in fluidcommunication with each of the pneumatic cylinders 16 for use inextending and retracting the pistons 16 a to selectively engage anddisengage the cargo container. More particularly, the pneumatic flowline connection ports couple to an external compressed air source thatprovides the pressurized gas that is required for actuation thepneumatic cylinders.

Connection housing 30 further includes three sampling line connections,referenced as 34 a, 34 b, and 34 c. Sampling line connections 34 a, 34b, and 34 c, allow for connection of tubular sampling lines used tocarry the sampled fumigant out from the interior of the cargo containerduring the fumigation process for sampling at a remote sampling station.The remote sampling station may be staffed by a member of the FDA orpersonnel trained to monitor fumigation methods and effectiveness. Thesampled fumigant is subsequently used to determine the concentration ofthe fumigant at specific times during the fumigation process. Indetermining the concentration of the fumigant within the cargocontainer, the monitoring personnel can determine whether or not therequired fumigant concentration level is reached, ensuring that allpotential pests are exterminated. As is defined by the standards setforth in the PPQ compliance agreement, gas must be sampled from at leastthree points within the cargo container. As a result, at least three gassampling flow line connectors are located within the line connectionhousing 30, however the design can be adjusted to incorporate theinstallation of multiple gas sampling flow line connectors, the numberof which being determined by the specific fumigation process. A mainfumigant introduction gas flow line connector 36 is provided to allowfor connection to a fumigant introduction line, through which fumigantis flowed into the cargo container. In addition, connection housing 30includes a gasket inflation connector 38, such as a Schrader valve, thatallows for connection of a compressed air line to selectively inflategasket 26, or alternatively allow for deflation of gasket 26. Asdiscussed above, gasket inflation connector 38 is in fluid communicationwith the inflatable bubble portion 26 b of gasket 26 whereby inflationof gasket 26 creates a generally air-tight seal with the inner structureof the shipping container. Finally, connection housing 30 includes anelectrical power connector 39. Electrical power connector 39 can be anysuitable means for coupling the containment door to an externalelectrical power source, and in the shown embodiment is a standardfemale electrical socket.

As best seen in FIG. 8, the back side of the portable containment door10, namely the side that faces inward towards the contained volumeduring the fumigation process, has a corresponding series of connectorsthat serve as a means of connecting the components that are used insideof the cargo container during fumigation. The connections includemultiple gas flow sampling line connectors 44 a, 44 b, and 44 c, thatprovide connection ports for sampling lines. The sampling lines areplaced in specific positions within cargo container and provide a meansfor out flowing fumigant samples during the fumigation process. Thesefumigant samples are used to determine the concentration of fumigantinside of the cargo container at specific times and positions. Thenumber of sampling gas lines and corresponding number of sampling gasline connectors that are required to take accurate readings of thefumigant concentration is determined by the standards set forth by thePPQ compliance agreement. In the shown embodiment, three gas samplingline connectors 44 a-c are present as is typical of the requirement formost cargo containers. However, the number of gas sampling lineconnectors 44 of the present invention can be adjusted duringmanufacturing to include any number of sampling line connectors as maybe required.

The connections further include a fumigant injection outlet port 46 thatallows for coupling of a fumigant introduction line, which issubsequently positioned in a specific region wherein a circulating flowof fumigant can be created within the cargo container. As should beapparent, front side connector 36 and back side outlet port 46 allow forthe introduction of fumigant through door 10 into the shipping containerfrom a fumigant gas source that is contained outside of the cargocontainer. The connections further include a gasket inflation line 48 influid communication with gasket 26 which functions as a conduit forpressurized gas, typically air, to inflate gasket 26. An electricalconnector 49 extends out from the back side of the door 10 to providepower to the electrical devices within the cargo container that arerequired for fumigation, and in particular circulation fans. Electricalconnector 49 can be any suitable connection means based upon the meansof electrical connection used by the devices that it is coupled to.Specifically, in the preferred embodiment, the electrical connector 49consists of two female electrical sockets, the standard for mostelectrical devices in the United States. Access door 14 provides thefumigation technician with easy access to the connection ports andoutlets located on the back side of door 10.

The method of performing a fumigation within a cargo container comprisesthe steps of first visually inspecting the cargo container for damage tothe outside that could cause fumigant to escape. If the cargo containeris fit for performing the fumigation, the required components forperforming the fumigation are positioned inside of the cargo container.These required components include the gas sampling lines, the mainfumigant introduction line, and the circulation fans. The ends of thegas and electrical flow lines that couple to the respective connectorson the back surface of the containment door are then placed so that theyare still within the cargo container, but in close proximity to wherethe back surface line connectors are positioned.

After the components within the cargo container are set up andpositioned correctly, the portable containment door is coupled to aforklift by threading the prongs of the forklift through the receivingchannel members 12 that extend from the front surface of the portablecontainment door. The portable containment door is then lifted andpositioned so that is within the frame of the main rear opening of thecargo container and so that the grooved flanges that support the hingedjoint of the cargo container doors are aligned adjacent to the pistonsof the pneumatic cylinders. Once the portable containment door ispositioned properly, the pneumatic cylinders are activated with theactuation of the outstroke function, causing the pistons of thecylinders to displace into the grooved flanges that extend from theframe of the cargo container rear opening. The displacement of thepistons into the grooved flanges limits the movement of the door,thereby locking it into place.

Once the door is locked into place, the compressed air source for theperipheral gasket is activated, causing compressed air to flow throughthe gasket gas flow line and into the gasket. The pressurized gas flowsinto the gasket, causing it to inflate. As the gasket inflates it exertsa force against the rear opening frame leading to the formation of aseal between the cargo container and the portable containment door. Withthe door locked in place and the seal formed, the user may then openhatch 14 on the front outer surface of the door allowing access to theinner electrical and gas flow lines. Then the user reaches in andconnects the lines to the associated line connectors on the back innersurface of the portable containment door. The lines and correspondingconnectors include the series of gas sampling lines, the fumigantintroduction line, and the fan electrical lines. Once the appropriatelines for performing the fumigation are connected inside of the spacewithin the cargo container to the back inner surface of the portablecontainment door, the hatch is closed. After the hatch is closed, theappropriate lines outside of the cargo container are connected to thecorresponding line connectors in the line connector housing that islocated on the front outer surface of the door. These lines include thepneumatic gas flow lines, the main fumigant introduction line, thegasket gas flow line, the electrical line, and the gas sampling lines.

Once the door is successfully installed with the lines connected, thepressurized fumigant source is activated, causing the flow of apredetermined amount of fumigant through the main introduction line andinto the space within the cargo container. In accordance with thestandard set forth by the PPQ compliance agreement, a USDA inspectorobtains gas samples from within the cargo container via sampling linesconnected to connection ports 34 a, 34 b, and 34 c. This sampled gas isflowed into a filter that includes Drierite®, a desiccant for removingwater moisture, and Ascartie®, an absorbing substance used for removingcarbon dioxide from the sampled gas. Once the sampled gas passes throughthe filter, it is then flowed into a fumiscope, where the concentrationof fumigant from the sampled gas obtained at a specific point within thecargo container is determined. As best illustrated in FIG. 14, fumigantconcentration levels are sampled, typically using three sampling tubes,to determine whether a predetermined concentration level has beenachieved throughout the contained volume. If the concentration level istoo low, then additional fumigant may be introduced. Conversely, if theconcentration level is too high, then the fumigation time may bereduced. Upon completion of the fumigation process, which includespassage of a predetermined period of time, the containment door isremoved and the aeration procedure is initiated in compliance withgoverning requirements and standards.

The present invention further contemplates adapting containment door 10with the following additional structural and functional features. First,door 10 may be adapted to include a heat exchanger in heat transfercommunication with the fumigant introduction line for the purposevaporizing the fumigant prior to introduction into the shippingcontainer. In addition, door 10 may have fans incorporated into the doorstructure to provide for post-fumigation aeration of the shippingcontainer. Finally, door 10 may be adapted with a vapor compressionrefrigeration unit (or air conditioning unit) for the purpose ofmaintaining a predetermined interior temperature within the shippingcontainer during the fumigation process. Providing a temperaturecontrolled interior is considered important in maintaining the qualityof perishable goods, particularly delicate goods such as flowers.

The instant invention has been shown and described herein in what isconsidered to be the most practical and preferred embodiment. It isrecognized, however, that departures may be made therefrom within thescope of the invention and that obvious modifications will occur to aperson skilled in the art.

What is claimed is:
 1. A method of fumigating the contents of acontainer having a main opening with at least one door, said methodcomprising the steps of: (a) placing at least one circulation fan, afumigant introduction line, and at least one gas monitoring line in atleast one predetermined position within the container; (b) placing aportable containment door in the container main opening in coveringrelation therewith; (c) forming a seal between the peripheral edge ofsaid containment door and the container; (d) electrically connectingsaid circulation fan to an external electrical power source; (e) fluidlyconnecting said fumigant introduction line to an external fumigantsource; (f) fluidly connecting each of said at least one tubular gasmonitoring lines to an external means for monitoring fumigantconcentration; (g) injecting fumigant into the container via saidfumigant introduction line until a predetermined fumigant concentrationis achieved; (h) monitoring fumigant concentration; and (i) maintaininga predetermined fumigant concentration for a predetermined time periodby selectively injecting additional fumigant.
 2. A method of fumigatingthe contents of a container according to claim 1, wherein said portablecontainment door comprises: a rigid main body sized in relation to thecontainer opening, said main body including peripheral edge; saidperipheral edge including an inflatable gasket configurable between adeflated configuration and an inflated configuration, said gasketdeployed in sealing engagement with said container when in said inflatedconfiguration; said main body further including an opening with a hatchconfigurable between open and closed positions for providing access tothe interior of said container when said main body is disposed incovering relation with said container opening.
 3. A method of fumigatingthe contents of a container according to claim 2, wherein said portablecontainment door further includes a fumigant introduction gas flow lineconnector for connection to a fumigant introduction line to allow forthe introduction of fumigant through the containment door.
 4. A methodof fumigating the contents of a container according to claim 2, whereinsaid portable containment door further includes at least one samplingline connection adapted for connection to at least one tubular samplingline to allow for monitoring of fumigant concentration within thecontainer.
 5. A method of fumigating the contents of a containeraccording to claim 2, wherein said means for securing said main bodyrelative to said container with said main body disposed in coveringrelation with said container opening includes at least one pneumaticcylinder having a piston selectively configurable for engaging anddisengaging the container.
 6. A method of fumigating the contents of ashipping container, said shipping container defining a main opening andincluding a pair of doors configurable between a closed configurationand an open configuration, said method comprising the steps of: (a)placing at least one circulation fan in the container; (b) placing atleast one fumigant introduction line in the container; (c) placing atleast one gas monitoring line in at least one predetermined positionwithin the container; (d) providing a portable containment door, saidportable containment door including a rigid main body sized for matingengagement with the container in substantial covering relation with thecontainer opening, said main body including peripheral edge, saidperipheral edge including an inflatable gasket for sealing engagementwith said container; (e) placing said portable containment door in thecontainer main opening; (f) forming a seal between the peripheral edgeof said portable containment door and the container; (g) electricallyconnecting said circulation fan to an external electrical power source;(h) fluidly connecting said at least one fumigant introduction line toan external fumigant source; (i) fluidly connecting said at least onegas monitoring line to an external means for monitoring fumigantconcentration; (j) injecting fumigant into the container via said atleast one fumigant introduction line until a predetermined fumigantconcentration is achieved; (k) monitoring fumigant concentration; and(l) maintaining a predetermined fumigant concentration for apredetermined time period by selectively injecting additional fumigant.